1. Field of the Invention
The present invention relates to a liquid discharging apparatus using a liquid discharging head to discharge ink and other liquids and a printing method using such an apparatus. More particularly, the invention relates to a printing apparatus and a printing method whereby to perform a given printing for a paper, cloth, unwoven cloth, OHP sheet, and other printing media. Furthermore, the present invention is effectively applicable to the provision of a printing apparatus capable of continuously printing a cloth having a printing width of one meter or more for a long period of time. As the specific equipment to which the present invention is applicable, there can be named various office equipment and mass-producing equipment such as printers, copying machines, facsimile apparatuses, and word processors. Further, there can be the apparatuses to drive an object by use of the liquid which is being discharged.
2. Related Background Art
As a conventional liquid discharging apparatus, there is the apparatus which performs the printing by discharging a liquid or utilizes a special liquid by discharging it. In general, the discharging portion which discharges a liquid is extremely small. Thus, the dyestuff or pigment mixed in a liquid creates a fixing state itself or foreign particles adhering to it disable the liquid to be discharged, leading to the defective printing of the printing apparatus, a problem that the discharging liquid cannot be utilized efficiently. Usually, therefore, the suction, pressurization, or the like known as recovery means is considered for use at an appropriate interval before such a problem occurs in order to cause the liquid to be forcibly exhausted, the discharging area in the discharging ports to be cleaned, or to eject air or liquid to the discharging area in the discharging ports for cleaning.
Nevertheless, while it is effective to dissolve and remove the exceedingly viscous ink or fixed substances in the discharging ports by ejecting a liquid to the discharging ports by such a recovery means as described above thereby to wash away the adhesive substances with the liquid, this method tends to create a problem that the printing density is lowered because the rinsing liquid is mixed with ink in the discharging nozzles the inside of which are negatively pressurized at that time, and causes the ink density to be reduced.
Also, with the recovery means which does not use any rinsing liquid, the exceedingly viscous ink adheres to the vicinity of the nozzles of the discharging head, thus tending to create clogging or the disabled ink discharging.
Also, in a case where the liquid is forcibly exhausted from the discharging ports by suction, there is a need for making the inner volume of the cap great in order to airtightly close the discharging head when it is sucked if the employed discharging head uses many numbers of discharging nozzles, and it becomes difficult to provide a given control in a negative pressure accordingly.
Also, for a method using only a sponge to be in contact with the discharging head for cleaning, there is a possibility that foreign particles are pressed into the nozzles to result in the disabled discharging if the employed discharging head is such as having fine nozzles of a 400-dpi resolution. Also, if this type of sponge is sufficiently wet, the liquid in the sponge is sucked into the nozzles due to the negative pressure in the nozzles to cause the ink density to be reduced, hence creating the problem that the printing density is lowered.
Further, in order to prevent the splashed mists from being accumulated on the head surface at the time of ink discharging to clog the discharging ports, it is conceivable that the head surface should be wiped off by a resilient rubber blade, but when an operation must be continued for long hours to meet an industrial requirement, there is a possibility that the wiped-off ink is accumulated without any particular place to dispose of it and becomes an exceedingly viscous ink. Thus, the discharging head is rubbed by a blade to which such an exceedingly viscous ink adheres, and in such a case, the disabled discharging is invited instead after all. Particularly, when a color printing apparatus is used, the mists are collected from its four heads, and a problem of the kind is more conspicuous.